1. Field of the Invention
The present invention relates to a heat-foamable sheet, a method for manufacturing the same, a foaming filler member, and a method for filling the inner space of a hollow member.
2. Description of Related Art
It has been conventionally known to fill a foamed body in a hollow member formed as the closed cross section of an automotive pillar or the like for the purpose of preventing the vibration and noise of an engine or wind noise from being transmitted into the vehicle interior of an automobile.
For example, it has been proposed to form such a foamed body by molding a foamable material into a specified configuration by injection or extrusion and foaming the molded material at 110 to 190° C. (see, e.g., Japanese Patent No. 2721327). It has also been proposed to, e.g., form a foamed body by molding a composition containing 30 to 42 parts by weight of rubber based on 100 parts by weight of the entire composition into a specified configuration and foaming the molded composition at 140 to 170° C. (see, e.g., Japanese Unexamined Patent Publication No. 62-62882).
It has been proposed to, e.g., form grooves in a foamable base material and form projections in a holder body such that the grooves and the projections form a foamed body guide and thereby fill a foamed body in the clearance between the corner portion of a hollow chamber and the apex portion of the foamable base material (see, e.g., Japanese Unexamined Patent Publication No. 2001-114037).
It has also been proposed to, e.g., fill a foamed body in an irregularly shaped hollow chamber having a protruding region. Specifically, a hollow chamber shutoff implement for shutting off the hollow chamber by foaming a foamable base material is provided with two holder plates for supporting the foamable base material and disposed in the hollow chamber. In the protruding region of the hollow chamber, the foamable base material has both side faces thereof supported by the two holder plates, while having one side face thereof supported by one of the holder plates in the region of the hollow chamber other than the protruding region. Then, the foamable base material is foamed such that the protruding region of the hollow chamber is filled with the resulting foamed body (see, e.g., Japanese Unexamined Patent Publication No. 2004-252169).
However, a foamable material molded by injection or extrusion such as disclosed in Japanese Patent No. 2721327 or Japanese Unexamined Patent Publication No. 62-62882 equally foams in all directions through heating. When the inner space has a configuration which is more protruding in one direction than in the opposite direction relative to the position of the foamable material disposed therein, a problem occurs in that the portion of the inner space protruding in one direction cannot be filled satisfactorily.
On the other hand, even when the inner space has the projecting portion mentioned above, the use of the foamed body guide disclosed in Japanese Unexamined Patent Publication No. 2001-114037 or the two holder plates disclosed in Japanese Unexamined Patent Publication No. 2004-252169 allows the protruding space portion to be filled with the foamed body. However, an extra member for filling the foamed body in the protruding space portion becomes necessary, which results in an intricate structure and leads to the problem of higher manufacturing cost.